Pinion Bearing
Preload
Set to: 5-15 in-lbs for used bearings / 25-35 in-lbs for new bearings
To increase preload – tighten pinion nut in small increments to
crush crush-sleeve
To decrease preload – install new crush-sleeve and start again

14-bolt Nomenclature

There are a few unique characteristics/parts
to the 14-bolt. The following pictures illustrate the terms I'm going to use
in the rest of the article.

A – Top. The
top of the gear tooth, a.k.a. Face, Top Land
B – Root. The bottom of the gear tooth, a.k.a. Flank
C – Heel. The outside-diameter-end of the gear tooth
D – Toe. The inside-diameter-end of the gear tooth
E – Coast. The concave side of the gear tooth*
F – Drive. The convex side of the gear tooth*

* Don’t be mislead
by the terms “coast” and “drive”, as the ring-gear
can be driven by the pinion on either side of the teeth. Which side of
the teeth will depend on if the gear-set is standard or reverse spiral
and whether the vehicle is going forward or in reverse.

Introduction

Setting up ring and pinion
gears may seem an intimidating job, but the entire process is really just a
matter of adjusting four separate but inter-related settings until they all
fall within specification. The four settings are:

BacklashDefinition: The amount by which a tooth space exceeds the thickness of
an engaging tooth.Think of it as: Play between the mating teeth of gears or how tightly
the ring and pinion gears mesh together.How Measured: Measured as the free movement of the ring-gear with pinion
held steady, in thousandths of an inch, using a dial indicator on the ring-gear.
In other words, you’re measuring how much you can rotate the ring-gear
before it engages the pinion teeth – this is the space between the teeth
– called “backlash.”Adjusted Via: Tightening and loosening the carrier adjuster nuts to move
the carrier either towards the pinion (decreasing backlash) or away from the
pinion (increasing backlash).Note: The purpose of having backlash (i.e. the reason gears aren’t
set-up tight, with no play) is to prevent the gears from jamming together. Lack
of backlash may cause noise, overloading, overheating, or seizing and failure
of the gears or bearings.

Backlash
- the amount by which a tooth space exceeds the thickness of an engaging
tooth.

Pinion
DepthDefinition: Position of pinion-gear relative to the ring-gear centreline,
expressed as either a mounting distance (measured from behind the pinion head
to the centreline of the ring-gear) or a checking distance (measured from the
face of the pinion head to the centreline of the ring-gear). Think of it as: How close the head of the pinion is to the centreline
of the ring-gear. Proper pinion depth makes sure the pinion teeth mesh with
the middle of the teeth on the ring-gear – between the top and the root.
Increasing pinion depth moves the pinion closer to the centreline of the ring-gear,
moving the pinion “deeper” into ring-gear teeth and reducing the
checking distance.How Measured: The final determination of correct pinion depth can only
be obtained by reading and interpreting the gear tooth contact pattern using
gear-marking compound. Adjusted Via: Shims placed between the axle housing and the pinion bearing
retainer. Adding shims moves pinion further away from ring-gear centreline,
moving the pattern from the root to the top. Removing shims moves pinion closer
to ring-gear centreline, moving the pattern from the top to the root.Note: When adjusting pinion depth, begin with a starting shim stack and
make large adjustments at first until the correct setting is bracketed; then
make progressively smaller adjustments until the final setting is achieved.
Increasing pinion depth decreases backlash and moves drive pattern slightly
towards toe, and coast pattern slightly towards the heel. The opposite is also
true - decreasing pinion depth increases backlash and moves the drive pattern
slightly towards the heel, and the coast pattern slightly towards the toe.

Pinion-bearing
PreloadDefinition: Bearing preload is a measure of the rolling resistance in
a bearing or “bearing stiffness”. As a bearing is pressed against
its race, the point or line of contact between the bearing and the race becomes
larger, friction increases and preload is said to be higher. Correct bearing
preload is a balance between bearing stiffness and the wear resulting from the
preloading.Think of it as: How tightly the pinion bearings are pressed into their
races and consequently how stiff they are to rotate.How Measured: An inch-pound torque wrench is used on the pinion nut to
measure the torque required to rotate the installed pinion.Adjusted Via: Tightening the pinion nut to progressively crush the crush-sleeve.
As the sleeve crushes, it forces the cups and cones into tighter contact, increasing
preload. This is a one-way process - if you crush it too much, you must replace
it and start again.Note: For a 14-bolt, pinion preload is specified for the pinion bearing
retainer removed from the axle housing and with the yoke and pinion oil seal
installed. Too little preload diminishes load-bearing capacity as the load-bearing
surfaces between rollers and race are decreased. Too much preload increases
friction, resulting in excessive noise, heat, and rapid wear.

Carrier-bearing
PreloadDefinition: See pinion-bearing preloadThink of it as: How tightly the carrier-bearings are pressed into their
races and consequently how stiff they are to rotate. Also controls how tightly
the carrier is held in the housing.How Measured: Not possible to measure directly.Adjusted Via: Turning the adjuster nutsNote: If carrier preload is too little, carrier will move away from pinion
under load (squirm or deflect), increasing backlash. This could lead to insufficient
gear tooth contact, resulting in chipping/breaking of gear teeth.

Tear Down

Loosen
lug-nuts and remove the axle-flange to hub bolts.

Jack
up axle, and secure safely on jack stands.

The job can be done
with the axle in or out of the vehicle. I found it actually easier to
do it with the axle still in the vehicle as I could then use the brakes
to apply load to the gears when checking the pattern - more on that later.

Tap
the axle shafts out of the axle with a brass drift. Remove the axles and
put them aside

Do not leave them,
covered in sticky gear oil, precariously leaning up against the wall in
the corner where you do all your cutting and grinding so that they can
fall over in the chips, slivers, and grinding dust...it doesn't aid the
installation later!

...Don't ask!

Remove
the diff cover bolts except for the top-most one. Pry / knock the cover
loose (be careful not to damage the sealing surface of the cover or axle
housing) and drain the gear oil. Make sure you have a large enough pan
- capacity is about 5.4 pints.

When the oil has drained,
remove the last bolt and the diff cover. Thoroughly clean the cover ready
for installation.

Remove
the driveshaft u-bolts or straps and disconnect the driveshaft from the
pinion yoke.

Before
tearing down the diff, check the existing backlash with a dial-indicator.

Strictly speaking,
this step is only necessary if you will be re-using the gears. The reason
you want to check it now, is so that you can re-install the same gears
with the original backlash (assuming it was within spec) to avoid changing
the gear tooth contact pattern since the gears have broken in together
at this lash. In many axles this wouldn't even be an option, but because
the 14-bolt has such a wide range of acceptable backlash (0.003"
- 0.012") it can be worth checking if you're going to be re-installing
the same gears.

I used new gears,
but checked anyway, just for interest's sake. Backlash was 0.030"...pretty
loose by anyone's standard!

Before removing the carrier, be sure to mark the carrier bearing caps so
that they can be re-installed in exactly the same orientation. I usually
stamp two horizontal dots on the top of the left bearing cap and on the
adjacent housing; and a single dot on the right.

Remove
the bolts securing the adjusting-nut locks.

Remove the adjusting-nut
locks.

Keep these small parts
in a safe place during the project.

...Don't ask!

Remove
the carrier bearing bolts and caps.

Loosen
the adjusting nuts so that the carrier can be removed, and carefully remove
the carrier. Be careful - it's quite heavy.Ahh - hooray
for the mighty 14-bolt - no prying the carrier out, no case spreader,
no cursing!

It's best to use the
proper spanner tool, but a #2 Phillips screwdriver will do.

The right adjusting
nut is loosened by moving the screwdriver handle DOWN.

The left adjusting
nut is loosened by moving the screwdriver handle UP.

In other words, the
adjusting nuts are both right-hand thread and screw into the housing.

If you
plan on re-using them, tag and keep the carrier bearing cups separate
so that they can be re-installed on their original sides.

Remove the carrier
bearings from the carrier.

Here I am using a clamshell-style
carrier bearing puller.

In the past I have used cheap
2-jaw pullers (that had to have the legs ground to fit in the carrier
reliefs below the carrier bearings), hammer and chisel, heel-style pry-bars,
and who knows what to remove carrier bearings.

None of these methods works
very well, all seem to damage the bearing during removal, and frankly
I was tired of them.

On top of that, the design
of the stock 14-bolt carrier leaves virtually no room to get a leg-style
puller or a bearing separator in behind the carrier bearings.

If you're re-using the carrier, scribe an alignment mark on both halves
so that it may be reassembled in the original orientation. If you're re-using
both the carrier and the ring gear (i.e. if you're just performing maintenance
on the differential inside the carrier), make the scribe line on the ring
gear as well so everything can be re-assembled in the original position.

Use a clamp or similar
device to keep pressure on the two halves of the carrier as you remove
the ring gear bolts because spring pressure from the differential will
try and force the two halves apart.

Remove and DISCARD
the old ring gear bolts and lock washers.

T tap the ring gear free from the carrier. You should properly use a soft-faced
hammer or brass drift.

Hey - I'm just holding
that screwdriver for illustrative purposes...I would, of course, never
use the wrong tool for the job....oh no...simply unheard of!

Before
removing the pinion nut, and with the carrier removed, it can be beneficial
to check the pinion bearing preload. This will give you some indication
as to the health (or in my case - lack thereof) of your pinion bearings.

To measure pinion
bearing preload - use a beam- or dial-type inch-pound torque wrench on
the pinion nut and measure the torque required to rotate the pinion. Do
not read the initial torque it takes to start the pinion turning, but
rather the steady torque it takes to keep the pinion rotating.

Mine was only 2 in/lbs
where the spec is 5-15 in/lbs for used bearings!

Note: Yes, the eagle-eyed
readers amongst you will notice that this is not a 14-bolt in the picture.
In fact, it looks suspiciously like a D60 front axle. Hey - sometimes
a picture doesn't turn out and you have to use what you have available.

Remove
the pinion nut. You will need a 1.5" socket to do so. Here, I am
using an impact wrench on the pinion nut and, to prevent the yoke turning,
a pipe wrench with a large extension on the handle so that it contacts
the floor.

Next, remove the 6
bolts and lock washers that secure the pinion bearing retainer to the
axle housing.

To remove the pinion
bearing retainer, you will probably have to use a brass drift to rap on
the straddle bearing journal from the other side of the housing.

Be careful not to
drive the retainer out of the housing forcefully so that it flies out
of the housing, bounces of the driveshaft, and skids across the floor...

...don't ask!

Carefully remove the
original pinion shims from the housing or the back of the bearing retainer.
Measure the thickness of each shim with a 0-1" micrometer, total
the numbers, and record this value as "original shim stack"
for use later when setting up the gears.

Once removed,
the pinion bearing retainer assembly looks like this.

View from the rear of the pinion bearing retainer with pinion installed.

I used
a small 20-ton shop press to press the pinion out of the yoke and bearing
retainer. If you ever want to re-use the pinion, be sure to get the press
nice and square and either use a soft end-cap or a brass plug in between
the press and pinion threads to avoid damaging the threads.

Also, have a box with
rags in it, or something similar, for the pinion to fall into when it
pops out - otherwise it will smash into the concrete shop floor and likely
damage the straddle bearing journal and/or pinion teeth...

...don't ask!

Here's
what the pinion looks like when removed from the bearing retainer

A view
from the rear of the bearing retainer, with the rear pinion bearing race
closest to the camera.

The 14-bolt pinion
bearing retainer is a unique and clever beast. It's really just a housing
that holds the races for the two pinion bearings - but what it allows
you to do is set up the pinion before assembling it into the axle housing.

Also, because it holds
the pinion and is removable from the axle housing - it means pinion depth
can be controlled simply by shimming this retainer when it's installed
into the axle housing. This means shims are not needed on the pinion itself,
under the bearings, to set depth; and therefore you don't need set-up
bearings and you don't need to remove and install bearings and shims to
adjust pinion depth. Simply pull the retainer, add or subtract shims between
it and the axle housing, and re-install.

To remove
the rear pinion bearing and old crush sleeve I used a large bearing separator
and the press.

Once again - be careful
not to damage the threads on the pinion and place something underneath
to catch the pinion when it falls.

With
the pinion removed, it's time to remove the seal and races from the bearing
retainer.

Clamp the retainer
securely in a vice.

I used a seal-pulling-sharp-pointy-like-thing*
tool to remove the seal. It's probably in there fairly tight, and you're
likely to ruin it getting it out.

* Note: probably not
the real name.

With the
seal removed, the front pinion bearing cone slides out.

You
are left with the retainer with just the two races installed.

Nice corrosion on
that race - no wonder preload was so out of spec!

Use
a brass drift and a hammer to knock out each race from behind.

Oops - looks like
I missed at least once and hit that thumb!

With both races removed,
give the retainer a thorough cleaning. Make sure no oiling passages are
blocked, and pay particular attention to ensuring that the back face of
the mounting flange (where the pinions shims go) is flat and true. Mine
had some rough edges where the extreme outside edge had gotten rock-rash
so I cleaned them up with a small machinist's hand file.

The
final step in disassembly is to remove the straddle bearing from the axle
housing. I used the trusty hammer and a large deep socket to carefully
drive it out.

If you are re-using
an old ring gear be sure to clean it thoroughly before installing it on
the carrier. Pay particular attention to ensuring the mounting surface
is clean and burr-free and that all the bolt holes are clean, free from
any grease or old thread-locking compound, and dry.

Ensure that the ring
gear mounting flange on the carrier is similarly clean and dry.

Heat the ring-gear
in a kitchen stove at 200°F for about 45 minutes to expand it slightly
and ease assembly. Note that this step is recommended only for new, clean
gears - unless of course your spouse doesn't mind the aroma of baking
gear oil! Never heat the ring gear with a flame as this will damage the
hardened surfaces. In a pinch, you could heat an old ring gear in boiling
water on a camp stove or the like.

If you're reusing
the old carrier and/or ring gear, ensure the parts are re-assembled in
their original positions by using the alignment marks you made earlier.

Carefully install
the ring gear onto the carrier, tapping with a soft-faced hammer if necessary,
being sure to line up the bolt holes.

DO NOT use the bolts
to pull the ring gear onto the carrier as this will damage the ring gear
bolts.

Apply
a little high-strength thread locking compound to the ring gear bolts
and carefully insert them. Don't go overboard with the thread locker -
only a little is needed. I find the new gel kind from Loctite works very
well.

Torque the ring gear
bolts evenly, in two or three stages, using a crosswise pattern, to 120
ft/lbs. You will have to carefully clamp the carrier in a vice to do this
- using a rag or something similar to prevent damage to the carrier.

Also, be aware that
most master install kits for the 14-bolt will not include ring gear bolts
- they have to be ordered separately. There are also two different length
bolts available - the correct one depends on the gear ratio being used.
Bolts for the 4.11 and down carrier are 1.8" long and bolts for the
4.56 and up carrier are 2.1" long. Note that neither length is the
same as any standard SAE bolt.

Obviously, since a
different part is required for each, and with such a small difference,
the exact length of thread engagement of the bolt into the ring gear is
critical.

This
pic shows a replacement ring gear bolt for a 4.11 carrier on top, with
original part, minus the lock washer, below.

Depending on the year,
original 14-bolt ring gear bolts may use split lock washers. Personally,
I don't like split lock washers and prefer to avoid them if at all possible
(see my Nuts & Bolts article
for reasons why); and my opinion wasn't altered any when I found four
or five cracked in half upon disassembling my original carrier. As such,
I was pleased to discover that the replacements from Randy's don't use
them, and are a flanged design instead.

If you are using stock-style
ring gear bolts that originally used a spit washer, you must also replace
the washers with new ones. If you delete the lock washers - the bolts
will be too long, as illustrated in the pic at left.

The
final thing to watch for is that the stock lock washers are much thicker
than standard SAE pieces. The pic at left shows a standard SAE 9/16"
grade 8 hardened lock washer on the left, and a stock 14-bolt ring gear
bolt lock washer beside it. You may find that sourcing the correct replacement
lock washers is difficult or ridiculously expensive (from a GM dealer).

In the end, your best
bet is probably just to order a set of new, replacement bolts from a reputable
vendor like Randy's Ring & Pinion. Be sure to order for the correct
gear ratio.

With
the ring gear installed, place the carrier on the bench and install the
carrier bearings. Install the left (non ring gear side) bearing first.

Carefully place the
bearing cone square on the journal.

Then press
it into place until the bearing seats firmly against the shoulder of the
bearing journal. I found that the bearing seated before the driver I was
using bottomed on the carrier journal.

The
right side is just a little more tricky since you already have a bearing
installed on the opposite side. This is because the rollers and cage protrude
slightly above the end of the carrier. If you were to simply set the carrier
on the press bed and press on the right side bearing, you would damage
the cage of the other bearing, ruining it.

To avoid this, I placed
a small driver underneath the carrier that fit inside the ID of the bearing,
against the end of the journal. This way, the load will transmit through
the carrier journal to the driver, to the press, without damaging the
installed bearing.

I then
pressed on the bearing, making sure the driver bore only against the inner
ring of the bearing cone, and not against the cage or rollers.

Reassembling
the Pinion

With
the carrier assembled you can move on to the pinion.

The first step is
to install the new pinion races into the bearing retainer.

I used the press and
a scrap of steel plate to initially press the rear race into the retainer.
However, to seat fully, the edge of the race has to be below the retainer.
I finished the last fraction of an inch by placing an old bearing in the
race and pressing on the centre of the bearing.

I used
the same "old-bearing" technique to seat the front race, as
it sits in the retainer quite a distance below the edge of the retainer.

In the pic you can
see I've placed a small aluminum seal driver between the end cap of the
press and the bearing.

A nice
thing about the 14-bolt design is that, unlike a Dana axle, there are
no baffles, slingers, or shims on the pinion to worry about. Also, because
pinion depth is controlled by shims between the bearing retainer and the
axle housing, there's no need to make or install set-up bearings - you
just go straight ahead and install the new bearings.

Install the rear pinion
bearing cone onto the pinion. I placed the race on the cone, then used
the press and a couple of pieces of square tubing to support the race
either side of the pinion, then pressed carefully on the straddle bearing
journal.

With the
rear pinion bearing in place on the pinion, place the completed bearing
retainer onto the pinion...

...and
it looks like this.

Slide the
crush sleeve onto the pinion shaft.

Then place
the front pinion bearing cone over the pinion shaft and into the bearing
retainer.

The
next step is the trickiest part of the whole procedure.

You need to press
the front pinion bearing cone onto the pinion shaft, seating it in its
race, without crushing the crush sleeve too much.

In order to get over
the pinion shaft you'll need to use a tube to bear on the inner ring of
the bearing cup. Here I'm using an old piece of 3" exhaust tube.

You
want to seat the bearing firmly, and even begin crushing the sleeve a
little to begin setting pinion bearing preload. This can save time and
effort later when you are tightening the pinion nut to crush the sleeve
and set final preload.

However, you don't
want to go too far. If you crush the sleeve too much at this point, you
will find that later, when you go to tighten the pinion nut, bearing preload
will be achieved before you get the pinion nut tight enough (once again
- don't ask how I know this!) On the other hand, if you just press the
bearing on loosely, and don't even begin to crush the sleeve, you can
have a hell of a job later, trying to start the sleeve crushing by tightening
the pinion nut. I've heard reports of it taking upwards of 500 ft/lbs
- which requires a heck of an impact gun or a seriously sturdy bench/vice
and a BIG breaker bar.

The trick is to use
the press to seat the bearing and just start the sleeve crushing. Once
the sleeve has started crushing - it takes a lot less torque on the pinion
nut to continue crushing it. Like crushing a beer can in you hands - once
it starts buckling it's much easier.

The best method is
to press a little at a time and check frequently how tight the bearing
is in its race. Once again - too far, and you'll find yourself later at
max bearing preload with the pinion nut torqued to only 100 ft/lbs - which
isn't really tight enough to keep it tight.

If you do cock it
up - you'll have to press the pinion out of the crush sleeve and front
bearing cone, install a new crush sleeve, and start again.

With the
front bearing pressed in place, coat the lips of the pinion seal with extreme
pressure grease, and place it over the pinion and into the retainer.

Tap the
seal into place with a mallet, being careful not to damage it. It's a tight
fit.

Place the
yoke on the pinion shaft splines...

...install
the pinion nut washer...

...and
install a brand new pinion nut.

I don't
care what anybody else says - never re-use an old pinion nut - always
use a new one. They are deformed-thread style locking nuts that play a
critical role. Not only does it have to be tight and stay-tight to keep
the pinion where it should be, but because of the crush sleeve design
- you're going to use this nut to set pinion bearing preload. Imagine
the stress in the threads when you're doing this and cranking that nut
down to three or four hundred ft/lbs!

If that doesn't convince
you - enlarge the picture at left and look at the threads of an old nut
compared to a new.

I spun
the pinion nut on until it was just snug using an impact gun on low and
a 1.5" socket.

I then
reverted to a 3/4"-drive torque wrench to do the final tightening.

Here you can see the
bearing retainer clamped securely in a vice (make it tight!) with a pipe
wrench on the yoke jammed against the bench to prevent the pinion from
turning.

Tighten the pinion
nut initially to 300-350 ft/lbs, then remove the torque wrench and yoke
holder and take a reading of the torque required to rotate the pinion,
using your in/lb torque wrench just as you did on disassembly.

Proper pinion bearing
preload is achieved when the torque required to rotate the pinion is 5-15
in/lbs for used bearings or 25-35 in/lbs for new bearings.

The
best tool for checking pinion bearing preload, on any axle, is a dial-indicating
torque wrench with a fairly small scale. This particular unit is an Armstrong
1/4' drive 0-75 in/lbs model. It also has a red indicator needle for recording
the maximum value attained.

Remember though -
it's the torque to keep the pinion rotating that you want to measure and
record - not the initial torque it takes to get it turning (which, typically,
can be anywhere from 10-30 in/lbs higher).

Installing
the Pinion

First,
install the new pinion straddle bearing into the housing by driving it
in from the front until is seats firmly.

Oh look - I haven't
managed to smash that thumb with the hammer yet!

Insert
the pinion bearing retainer, with pinion installed, into the axle housing.
At this point I just re-used the original pinion depth shim between the
retainer and axle housing as I like to set backlash before worrying about
pinion depth.

When installing the
bearing retainer, make sure that the oiling port on the retainer (yellow
arrow) matches up with...

...the
oiling galley in the axle housing (red arrow). Strangely, no manual I
have ever read mentions this - which is strange because the bolt pattern
is symmetrical, meaning you could overlook this step and still install
the retainer in the housing...with predictably disastrous results!

Don't ask!

When
installing the pinion bearing retainer assembly into the axle housing,
the journal on the head of the pinion will have to be driven into the
bore of the straddle bearing.

It's a tight fit but
shouldn't require you to pound it in. Use a brass drift on the end of
the pinion to tap the retainer and pinion into place.

Install
the six bearing retainer bolts and lock washers and torque in a crosswise
pattern to 65 ft/lbs.

Of note, the stock
3/8-NC16 bolts used to secure the pinion bearing retainer to the axle
housing (middle) are neither 3/4" nor 1" in length.

I wanted to replace
mine, so I checked the depth of the tapped blind holes in the axle housing
and discovered that the longer 1" bolts work fine without bottoming.

Installing
Carrier into Housing and Setting Backlash and Carrier Preload

With
the carrier bearing races installed, place the carrier in the axle housing.

Using the punch marks
made earlier, install the carrier bearing caps in their original positions
and tighten them until just snug. Over tightening them at this point will
freeze the carrier bearings in their bores and interfere with setting
carrier preload.

Loosen the right-side
adjusting nut and tighten the left-side adjusting nut until the ring gear
contacts the pinion without binding. This is zero backlash.

Tighten right-side
adjusting nut until carrier is forced into solid contact with left-side
adjusting nut. Loosen right-side adjusting nut until it is free from bearing
contact, then re-tighten until contact is re-established.

Now tighten right-side
adjusting nut two slots if carrier bearings are reused or three slots
if carrier bearings are new.

The carrier bearings
are now properly preloaded. After this step, if one adjusting nut is loosened,
the other must be tightened an equal amount to maintain carrier bearing
preload.

Backlash should now be checked at a minimum of two different places
on the ring gear. The dedicated will check backlash in four equally spaced places,
and the truly devout will measure the axial run-out of the ring-gear, mark the
high, low, and average spots, and use them to measure backlash.

Whichever
method you choose, read the backlash as follows:

1. Install dial indicator
on the axle housing so that it is as perpendicular as possible to the
ring-gear tooth. You want to place the button against the top-heel of
the tooth, and arrange it so that the shaft is as close as possible to
90 degrees to the tooth at that point

2. Hold pinion steady,
rotate ring-gear as far as it will go, check indicator button is against
tooth, set indicator to 0

3. While holding
pinion steady, rotate ring-gear as far as it will go in the opposite direction
and take reading.

Backlash should be
between .003" - .012", with .005"-.008" preferred,
and with no variance greater than .002. If you cannot get consistent readings
it is advisable to use the dial indicator to check the axial and lateral
run-out of both the ring-gear and the carrier mounting flange to determine
where the problem lies. If neither exhibits run-out of greater than .002"-.003"
the problem may lie in a bent housing.

My technique was to rotate the yoke until I could hook the fingers
of my right hand around the ears of the yoke and lock the yoke in place with the
heel of my palm against the housing. I then installed the dial indicator with
the shaft compressed a little, knelt in front of the housing, grasped the yoke
with my right hand as described, then used my left hand to grasp the head of a
ring gear bolt and used it to turn the ring gear as far as it would go one way.
Keeping pressure on the ring gear with a couple of fingers on the ring gear bolt
head, I then used thumb and finger on my left hand to rotate the dial indicator
to zero. Then, still keeping my right hand locking the pinion from turning, I
rotated the ring gear the opposite way using the ring gear bolt head while observing
the dial indicator and reading the backlash. Using this method I was able to rock
the ring gear back and forth by the ring gear bolt head while observing the dial
indicator to ensure a consistent, accurate measurement of the backlash.

If backlash is not within
spec, adjustments are made with the adjusting nuts as follows:

1. Remove the adjusting
nut locks, washers, and bolts and set aside.

2. Loosen the carrier bearing
cap bolts until they are just snug.

3. If backlash is more than
.012", loosen right-side adjusting nut one slot and tighten the left-side
adjusting nut one slot.

4. If backlash is less than
.003", loosen left-side adjusting nut one slot and tighten the right-side
adjusting nut one slot.

Remember that the right
adjusting nut is loosened by moving the screwdriver handle DOWN - the left adjusting
nut is loosened by moving the screwdriver handle UP.

Setting
Pinion Depth

In the
14-bolt, pinion depth is controlled by shimming the pinion bearing retainer.
The shims are shown at the far right in this pic.

The shims
are placed between the mounting flange of the bearing retainer (blue arrow)...

...and
the mounting surface on the axle housing (blue arrow).

In order to set pinion depth,
calculate a starting shim stack (a shim stack is the total thickness of one
or more shims used together), install it, check the gear contact pattern, and
then adjust the shim stack as indicated by the pattern.

To determine the proper
starting shim stack, proceed as follows:

1. Examine the head of the
new pinion for a pinion depth code marking. Do the same for the old pinion.

2. Based on the depth codes
of the two pinions, use the chart below to calculate the adjustment required
to the original shim stack. If a pinion does not have a depth code, assume it
to be "0" (the code, that is, not the adjustment).

3. Adjust the value of the
original shim stack by the amount indicted in the chart.

e.g. If the original
shim stack was .014", the original code was "-1" and the
new code is "+2", the correct thickness of the new shim stack
would be .014 + .003 = .017"

Table
for calculating shim adjustment from pinion depth codes

Depth
code of original Pinion

+2

+1

0

-1

-2

Depth
code
of new pinion

+2

0

Add .001

Add .002

Add .003

Add .004

+1

Subt. .001

0

Add .001

Add .002

Add .003

0

Subt. .002

Subt. .001

0

Add .001

Add .002

-1

Subt. .003

Subt. .002

Subt. .001

0

Add .001

-2

Subt. .004

Subt. .003

Subt. .002

Subt. .001

0

With
the starting shim stack calculated, proceed as follows:

1. Ensure that mating
surfaces of bearing retainer and axle housing are clean.

2. Place the pinion depth shims on the bearing retainer.

3. Carefully line up the bolt holes in the retainer, shims, and housing.

4. Install the
bearing retainer assembly in the housing, making sure the journal on the
pinion head seats in the straddle bearing.

5. Install the
six bearing retainer bolts and lock washers and torque in a crosswise
pattern to 65 ft/lbs.

6. Check the
gear contact pattern.

Checking the
Contact Pattern

To check
the contact pattern, proceed as follows:

1. Clean ring-gear
teeth and wipe any oil out of the housing.

2. Using a small, stiff brush, apply gear-marking compound to three or
four teeth of the ring gear, in at least two different places. Use the
marking compound sparingly, but be sure to completely cover both the coast
and drive side of the teeth. Some folks like to mix a little gear oil
with the marking compound to aid in application but I found using it straight
worked best for me. If you have new gears or gears with a dark finish
the yellow coloured compound works well, but if you have used gears or
gears with a silver or metallic finish, you may have more success with
the blue coloured marking compound – a popular brand is “Prussian
Blue” made by Permatex.

THIS NEXT STEP
IS THE MOST OFTEN IGNORED STEP - AND THE #1 REASON PEOPLE HAVE TROUBLE READING
THE CONTACT PATTERN

In order to produce a clear,
readable contact pattern you must apply a load on the gears when you rotate
them. You need to apply a load so that it takes 40-50 ft-lbs of torque to rotate
pinion.

3 . I have seen folks use a pry bar, forearm, heavy rags, or similar devices
to apply drag to ring-gear so that it takes 40-50 ft-lbs of torque to rotate
the pinion. However, by far the best method I have found is to temporarily
reinstall the axle shafts, and then use the brakes to apply the load. If you
have a helper, you can have them hold the brakes on slightly while you use
a torque wrench on the pinion nut to turn the pinion and check that the correct
load is being applied. If you have a parking brake on the rear wheels, you
could lightly apply it to create the load. If you have drum brakes and no
helper, you could temporarily adjust the rear shoes so that they contact the
drums enough to supply the required load. If you have them, you could also
use cutting brakes just slightly applied (this is the method I used). Finally,
if none of that works for you, you could try re-installing the wheels and
jacking them up to a point where they just contact enough of the ground to
provide the load required.

It may seem a lot of trouble,
but you will not get the best pattern without loading the gears, nor will you
achieve optimum setup.

4. With the load on the
gears in place, rotate the pinion two or three times in each direction through
the marking compound. Excessive turning of the ring gear is not advisable.

6. Observe
and record whether the pattern is towards the top or towards the root
of the ring gear teeth. Also note whether contact is at the heel or toe
of the teeth.

For the top - root
contact check you can use either the drive or the coast side pattern,
as the indication of pinion depth is the same on either side. In the case
of used gears it is sometimes easier to read the coast side pattern due
to wear on the gear teeth.

In this picture we
can see that my initial pattern displayed top/heel contact - indicating
that the pinion depth needs to be increased (shims removed) and the backlash
decreased slightly.

Drive
Side Contact Pattern Interpretation

Refer
to the diagram at left and adjust pinion depth by adding or subtracting
shims as follows:

a. If the pattern is towards the root, the pinion is too deep and must
be moved away from the ring gear centreline by increasing the shim stack.
b. If the pattern is towards the top, the pinion is not deep enough and
must be moved closer to the ring gear centreline by subtracting from the
shim stack.
c. Add or subtract shims in large increments at first until the correct
setting is bracketed; then make progressively smaller adjustments until
the final setting is achieved. As you home in on the ideal setting, adding
or subtracting a single shim of one thou can, and does, make a difference.

As a result you should
re-check and adjust backlash after each shim stack adjustment before re-reading
the pattern.

If you are having
trouble juggling pinion depth and backlash, try setting backlash to the
middle of the range, and then concentrating on pinion depth by concerning
yourself only with the position of the pattern between the root and the
toe. Once you get close to a good pinion depth pattern, re-check and re-set
backlash.

Fine-tuning Overall
Contact Pattern

By the time you have adjusted the pinion depth to centre the pattern between
top and root, and if you have held backlash to within spec you should have
an acceptable overall contact pattern. Ultimately you are aiming for a pattern
that is centred between the heel and toe and also centred between the top
and root of the tooth. There should be some clearance between the pattern
and the top of the tooth. On the coast-side the pattern may be slightly
towards the toe. The pattern should also be broad and diffuse, without sharp
edges.

If, however, you are not
satisfied with the location of the pattern between the heel and toe, you may
be able to fine-tune the pattern further by adjusting backlash slightly while
keeping it within the acceptable range. The following table summarizes the possible
adjustments. Keep in mind that adjusting backlash will also affect pinion depth
so that you may have to make further fine adjustments to the pinion shim stack
while you home in on the perfect settings.

All that
remains is to slap the axle shafts back in, torque the flange-to-hub bolts
evenly in a crosswise pattern to 115 ft/lbs, reinstall the wheels, reconnect
the driveshaft to the pinion yoke, lower the beast to the ground, break
in the gears, and hit the trails.

Break In

It is absolutely essential that all new gear-sets are properly broken in before
being heavily loaded (towing, constant use, and high load or rpm). During the
break-in period the gears settle in and often small metal particles or phosphorous
coating can be sloughed off. The goal is to have the gears settle in and then
change the oil and remove any particles before heavily loading the gears.